Research On Calculation Theory And Method Of Anti-Overturning Of Straight Single-Column Bridge

Bridge with single pier has the advantages of saving space and cost,therefore single-column bridge has been widely used in highway and city interchange since the 50’s of last century.However growing economy leads to traffic volume increase,with the increase of overloading vehicles,more and more single-column bridge collapse accidents are reported.Take the Chunhui Bridge and Harbin Bridge,two typical straight single-column bridges,as the research object,this thesis makes a systematic research on the mechanism of overturning failure for the box girder of straight single-column bridge under overload and partial load,and then the main factors that affect single-column bridge overturning are investigated deeply.The anti-overturning capacity practical calculation method and simplified calculation method are constructed by establishing the interaction between box beam,abutment and pier,and a method for recommending standard is put forward,which has a good theoretical and practical significance for the design of anti-overturning of the single-column bridge.This thesis researched four aspects as follow:(1)According to investigation to the wreckage of several collapsed single-column bridges,four kinds of failure mode of the single-column bridge are systematically proposed.(2)Take the box girder as a deformable body rather than the traditional rigid body,the practical anti-overturning calculation method of the single-column is presented.(3)The simplified calculation method for straight single-column bridge without considering the beneficial effects of self weight and large rotation is proposed in order to facilitate the practical application.And a method for recommending standard is put forward based on the structure reliability theory.(4)Take Chunhui Bridge and Harbin Bridge as example,the practical and simplified calculation method and standard method are verified.The results indicate as follow:(1)The overturning calculation methods in the existing codes are mainly based on the rotation of rigid body,which makes the anti-overturning ability of the single-column bridge is overestimated.(2)The practical anti-overturning calculation method can be used to simulate the critical overturning load.(3)Increase bearing transverse size or the linear gravity or the distance of end supports can significantly improve the anti-overturning bearing capacity of single-column bridges.